Details

Autor(en) / Beteiligte

• Alsop, David C.
• Ercan, Ece
• Girard, Olivier M.
• Mackay, Alex L.
• Michal, Carl A.
• Varma, Gopal
• Vinogradov, Elena
• Duhamel, Guillaume

Titel

Inhomogeneous magnetization transfer imaging: Concepts and directions for further development

Ist Teil von

• NMR in biomedicine, 2023-06, Vol.36 (6), p.e4808-n/a

Ort / Verlag

England: Wiley Subscription Services, Inc

Erscheinungsjahr

2023

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Off‐resonance radio frequency irradiation can induce the ordering of proton spins in the dipolar fields of their neighbors, in molecules with restricted mobility. This dipolar order decays with a characteristic relaxation time, T1D, that is very different from the T1 and T2 relaxation of the nuclear alignment with the main magnetic field. Inhomogeneous magnetization transfer (ihMT) imaging is a refinement of magnetization transfer (MT) imaging that isolates the MT signal dependence on dipolar order relaxation times within motion‐constrained molecules. Because T1D relaxation is a unique contrast mechanism, ihMT may enable improved characterization of tissue. Initial work has stressed the high correlation between ihMT signal and myelin density. Dipolar order relaxation appears to be much longer in membrane lipids than other molecules. Recent work has shown, however, that ihMT acquisitions may also be adjusted to emphasize different ranges of T1D. These newer approaches may be sensitive to other microstructural components of tissue. Here, we review the concepts and history of ihMT and outline the requirements for further development to realize its full potential. ihMT creates images that are sensitive to the dipolar order relaxation time in motion‐constrained molecules by comparing single and dual frequency magnetization transfer. ihMT concepts are reviewed and future needs and developments are outlined.